title: Height-independent estimation of glomerular filtration rate in children: an alternative to the Schwartz equation.
abstract: OBJECTIVE
  To compare the diagnostic performance of 2 height-independent equations used to calculate estimated glomerular filtration rate (eGFR), those of Pottel (eGFR-Pottel) and the British Columbia Children's Hospital (BCCH) (eGFR-BCCH), with the commonly used Schwartz equation (eGFR-Schwartz).
  
  
  METHODS
  We externally validated eGFR-Pottel and eGFR-BCCH in a well-characterized pediatric patient population (n = 152) and compared their diagnostic performance with that of eGFR-Schwartz using Bland-Altman analysis. All patients underwent glomerular filtration rate measurement using the gold standard single-injection inulin clearance method (GFR-inulin).
  
  
  RESULTS
  Median GFR-inulin was 92.0 mL/min/1.73 m² (IQR, 76.1-107.4 mL/min/1.73 m²). Compared with GFR-inulin, the mean bias for eGFR-Schwartz was -10.1 mL/min/1.73 m(2) (95% limits of agreement [LOA], -77.5 to 57.2 mL/min/1.73 m(2)), compared with -12.3 mL/min/1.73 m² (95% LOA, -72.6 to 47.9 mL/min/1.73 m(2)) for eGFR-Pottel and -22.1 mL/min/1.73 m² (95% LOA, -105.0 to 60.8 mL/min/1.73 m(2)) for eGFR-BCCH. eGFR-Pottel showed comparable accuracy to eGFR-Schwartz, with 77% and 76% of estimates within 30% of GFR-inulin, respectively. eGFR-BCCH was less accurate than eGFR-Schwartz (66% of estimates within 30% of GFR-inulin; P < .01).
  
  
  CONCLUSIONS
  The performance of eGFR-Pottel is superior to that of eGFR-BCCH and comparable with that of eGFR-Schwartz. eGFR-Pottel is a valid alternative to eGFR-Schwartz in children and could be reported by the laboratory if height data are not available.
authors.affiliation: Department of Pediatric Nephrology, VU University Medical Center, Amsterdam, The Netherlands; Department of Pediatric Oncology/Hematology, VU University Medical Center, Amsterdam, The Netherlands. Electronic address: h.blufpand@vumc.nl.
authors.forename: Hester N
authors.initials: HN
authors.lastname: Blufpand
authors.forename: Rik
authors.initials: R
authors.lastname: Westland
authors.forename: Joanna A E
authors.initials: JA
authors.lastname: van Wijk
authors.forename: Elianne A
authors.initials: EA
authors.lastname: Roelandse-Koop
authors.forename: Gertjan J L
authors.initials: GJ
authors.lastname: Kaspers
authors.forename: Arend
authors.initials: A
authors.lastname: Bökenkamp
mesh_terms: D000293:Adolescent; D001827:Body Height; D002648:Child; D002675:Child, Preschool; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007223:Infant; D008297:Male; D008433:Mathematics; D012189:Retrospective Studies; D055815:Young Adult
keywords: BCCH; British Columbia Children's Hospital; CKD; Chronic kidney disease; Estimated glomerular filtration rate; Estimated glomerular filtration rate according to the British Columbia Children's Hospital equation; Estimated glomerular filtration rate according to the Pottel equation; Estimated glomerular filtration rate according to the Schwartz equation; GFR; GFR-inulin; Glomerular filtration rate; Glomerular filtration rate measured by the single-injection inulin clearance method; IDMS; Isotope dilution mass spectrometry; LOA; Limits of agreement; eGFR; eGFR-BCCH; eGFR-Pottel; eGFR-Schwartz